The nation's largest TV station owner is gearing up to fight for deregulation, and it wants some of its newsroom managers to join the effort.

Sinclair Broadcast Group is asking its executives - including the news directors at its many stations - to contribute to its political action committee, a move that journalism ethics experts say is highly unusual and troubling.

"Please take the time to evaluate the importance that the Sinclair PAC can have towards benefiting our company and the needs of the industry as a whole," reads an employee solicitation letter from David Amy, vice chairman of Sinclair and chairman of its PAC.

Sinclair, based in the Baltimore suburb of Hunt Valley, is the largest station owner in the country, with 173 outlets. It is poised to become even larger with its pending $3.9 billion purchase of Chicago-based Tribune Media, which owns or operates 42 stations in cities such as New York, Los Angeles and Chicago, including WGN-TV.

The company is fighting to preserve an arcane rule adopted by the Republican-dominated Federal Communications Commission last year that effectively enabled it and other big media companies to buy more stations. If Congress were to restore the old limits, or if a pending court challenge succeeds, it could complicate Sinclair's acquisition of Tribune.

But encouraging its news directors to contribute to its political effort, in the view of some experts, breaches a long-standing ethical obligation among journalists.

Rebecca Hanson, Sinclair's senior vice president of strategy and policy, said there was nothing compromising about the company's request. She said it was sent to newsroom managers only, not to reporters, anchors or other lower-level news employees. The news directors "were solicited as a result of being part of our managerial level, not because of their role in editorial," she said.

She added, "Participation is completely voluntary. There is no corporate pressure to participate and no consequence for not participating. It doesn't put them in any ethical bind whatsoever."

Under campaign finance regulations, any contributions would be disclosed in federal filings.

Major TV news outlets such as ABC, CBS, CNN, Fox News and NBC say they prohibit their journalists from contributing to political parties, candidates or causes, and don't ask them to chip in to the company's PAC. The prohibition is aimed at eliminating the perception of partisanship by journalists.

Given that tradition, Sinclair's policy "violates every standard of conduct that has existed in newsrooms for the past 40 or 50 years," said Lewis Friedland, a journalism professor at the University of Wisconsin and a former TV news producer. "I've never seen anything like this. They certainly have the right to do it, but it's blatantly unethical."

By contributing money to Sinclair's lobbying efforts, he said, news directors would be tacitly supporting the company's agenda, potentially raising doubts about their stations' impartiality and independence when reporting on controversial issues, such as city or state legislative debates about deregulation. "It would cause people to ask whether they're being fair and balanced in their coverage," he said.

Scott Livingston, Sinclair's vice president of news, did not respond to requests for comment.

In addition to breaking with journalistic tradition, the company's request could put its news directors in an untenable position, said Mark Feldstein, a professor of broadcast journalism at the University of Maryland. Despite Sinclair's official reassurances, said Feldstein, a former local and network TV reporter, some news directors might feel that opting out would be perceived by their superiors as an act of disloyalty.

As this column stated in August, a Sinclair-Tribune merger will create the...

"Since the change in administration last year, we now have an FCC Chairman who appreciates the role of local broadcasting enough to launch a number of politically unpopular deregulatory initiatives necessary to ensure the future of our industry," Amy's letter says. "In response, there have been Congressional efforts to counter these actions, such as a legislative proposal to (limit station ownership), which will prevent any broadcaster from meaningful growth in the future ... We need allies in Congress who understand the role of local television and who are willing to defend it in today's ever-changing landscape."

Congressional action to overturn the FCC station-ownership rule is less likely than a court decision, said Andrew Jay Schwartzman of Georgetown Law School, who is representing a coalition of public-interest groups that has challenged the rule. The case will be argued in April.

During the 2016 campaign, Sinclair - controlled by the founding Smith family - was criticized for reportedly ordering its many local stations to air news stories favorable to Donald Trump on a mandatory, or "must-run," basis. Sinclair stations in "battleground" states aired far more interviews with Trump and his surrogates than those featuring his rival, Hillary Clinton; Sinclair officials said the Trump campaign was more accessible to Sinclair's reporters than was Clinton or her surrogates. It said Clinton's campaign was offered the same number of interview opportunities as Trump but chose not to participate.

Sinclair's stations also air conservative-leaning commentaries from Mark Hyman, a Sinclair executive. Last April, the company hired former a Trump White House aide, Boris Epshteyn, to be its chief political analyst; it now distributes his commentaries to its stations for airing on their local newscasts.

In 2004, Sinclair announced it would air a documentary critical of Democratic presidential candidate John F. Kerry but backed down amid pressure. It drew further criticism from Democrats on the eve of the 2012 election when its stations in several battleground states aired a half-hour news "special" that faulted President Barack Obama for his handling of the economy, his signature health-care law and the terrorist attack on a U.S. installation in Benghazi, Libya.

Sinclair has no existing presence in Chicago, where WGN-Ch. 9 and cable channel WGN America are headquartered. Tribune Media once owned the Chicago Tribune and other American newspapers, until the former Tribune Co. was split in two in 2014. Tribune Media kept the broadcast entities and real estate properties, including Chicago's Tribune Tower, while Tribune Publishing, now called Tronc, kept the print publications.